Once upon a time, I received a phone call from an entrepreneur who told me that she was going to build the best online dating site ever: Fuego Connect. The problem with dating sites, she said, was that you have to sift through so many people who are nothing like you. Wouldn't it be great to have a website where everyone on the site shared your same passions?

So if you were a black diamond skier with a home in Aspen, you'd have access to other wannabe slalom champs. If you had three dogs, you'd find a man who was similarly mad about his pugs. If you were into spirituality, you'd have an all access pass to other men who were seeking nirvana. She wanted to know what I thought and if I'd like to be involved. I told her, point blank, that this was the worst idea of all time.

(Okay, maybe I was slightly more diplomatic, but, knowing me, I probably wasn't.)

The problem with a site that connects people over "passions" is that sharing such interests says nothing about one's ability to forge a 40-year romantic relationship. By extolling the merits of relationships based in gardening or hip-hop music, FuegoConnect would be exacerbating the problem, by bringing people together over superficial hobbies that weren't at all relevant to long-term compatibility. After hundreds of dates, thousands of hours of dating coaching, I've become irrevocably convinced that common interests are the LEAST important element in happy relationships. They are the icing, but they are certainly not the cake.

Teenagers might fall in love because both of them list Belle and Sebastian as their favorite band. Adults, at a certain point, should know better, right? But we don’t.

Jody is a long-distance biker who trains for two hours a day and she wants a man who shares her passion. Not only is that less than 5% of the population, but consider the other characteristics of the long-distance biker — he puts more time into training than he does into relationships. This is why the Wall Street Journal actually wrote an article about "marathon widows" — women who marry men who are more dedicated to their sport than to their families. But hey, at least they have "fitness" in common!